Department of Emergency, The Second Affiliated Hospital of Xi'an Jiao Tong University, Xi'an, China.
Lab of Clinical Immunology and Pathogen Detection, Xi'an Medical University, Xi'an, China.
Biochem Biophys Res Commun. 2019 Jan 1;508(1):169-176. doi: 10.1016/j.bbrc.2018.11.074. Epub 2018 Nov 22.
Lipopolysaccharide (LPS) induces macrophage/monocyte activation and pro-inflammatory cytokines production by activating Toll-like receptor 4 (TLR-4) signaling. Rab GTPase 21 (Rab21) is a member of the Rab GTPase subfamily. In the present study, we show that LPS induced TLR4 and Rab21 association and endosomal translocation in murine bone marrow-derived macrophages (BMDMs) and primary human peripheral blood mononuclear cells (PBMCs). In BMDMs, shRNA-mediated stable knockdown of Rab21 inhibited LPS-induced expression and production of pro-inflammatory cytokines (IL-1β, IL-6 and TNF-α). Conversely, forced overexpression of Rab21 by an adenovirus construct potentiated LPS-induced IL-1β, IL-6 and TNF-α production in BMDMs. Further studies show that LPS-induced TLR4 endosomal traffic and downstream c-Jun and NFκB (nuclear factor-kappa B) activation were significantly inhibited by Rab21 shRNA, but intensified with Rab21 overexpression in BMDMs. Finally, in the primary human PBMCs, siRNA-induced knockdown of Rab21 significantly inhibited LPS-induced IL-1β, IL-6 and TNF-α production. Taken together, we suggest that Rab21 regulates LPS-induced pro-inflammatory responses by promoting TLR4 endosomal traffic and downstream signaling activation.
脂多糖 (LPS) 通过激活 Toll 样受体 4 (TLR-4) 信号通路诱导巨噬细胞/单核细胞活化和促炎细胞因子的产生。Rab GTPase 21 (Rab21) 是 Rab GTPase 亚家族的成员。在本研究中，我们表明 LPS 诱导 TLR4 和 Rab21 在小鼠骨髓来源的巨噬细胞 (BMDMs) 和原代人外周血单核细胞 (PBMCs) 中的关联和内体易位。在 BMDMs 中，shRNA 介导的 Rab21 稳定敲低抑制了 LPS 诱导的促炎细胞因子 (IL-1β、IL-6 和 TNF-α) 的表达和产生。相反，通过腺病毒构建体强制过表达 Rab21 增强了 BMDMs 中 LPS 诱导的 IL-1β、IL-6 和 TNF-α 的产生。进一步的研究表明，Rab21 shRNA 显著抑制了 LPS 诱导的 TLR4 内体运输以及下游 c-Jun 和 NFκB (核因子-κB) 的激活，但在 BMDMs 中过表达 Rab21 则加剧了这一过程。最后，在原代人 PBMCs 中，Rab21 的 siRNA 诱导敲低显著抑制了 LPS 诱导的 IL-1β、IL-6 和 TNF-α 的产生。综上所述，我们认为 Rab21 通过促进 TLR4 内体运输和下游信号激活来调节 LPS 诱导的促炎反应。
